Stacking pieces of material in an accurate and precise fashion to form stacks having various profiles can be done manually by hand and unassisted when they are large and easy to handle. However, for micro manufacturing applications, when the piece of material is smaller, specialized micromanipulation tools are necessary to assist in stacking. Further, unassisted manual processes are imprecise in terms of placement and off-set adjustment resulting in end products that may not be within specified tolerances. For example, stack tolerance can vary significantly affecting overall dimensions of the device of interest.
In particular, pieces of material having one or more sub-millimeter dimensions, light-weight material and/or very flexible material (e.g. plastic strips) are difficult to handle. Further, as material properties change (e.g. density, volume) there is a greater tendency, particularly for longer pieces of material, to warp or buckle thereby increasing the difficulty of constructing accurately and precisely positioned stacked piles of the material. At sub-millimeter thicknesses (e.g. a few tens of microns), pieces of material are especially difficult to handle for stack fabrication applications.
There remains a need in the art for a method and apparatus to assist in the accurate and precise stacking of pieces of material, particularly pieces of material having sub-millimeter thicknesses.